BGP best-path selection algorithm on Meraki MX one-armed concentrator

CSV
Comes here often

BGP best-path selection algorithm on Meraki MX one-armed concentrator

Hi,

 

Does anyone have Meraki documentation related to BGP best-path selection algorithm?

 

From my testing environment I've noticed that a MX in one-armed concentrator mode (the only mode that supports eBGP) always prefers the eBGP route over iBGP route (it doesn't care of AS-PATH length)

 

Ex:

 

R1(AS 100)----eBGP----HUB1-----iBGP(AS 65100)-----HUB2----R2 (AS 200)

 

R1 advertises subnet 10.10.10.10/32 with AS path 100 100 100

R2 advertises subnet 10.10.10.10/32 with AS path 200

 

 

--> Hub1 prefers the external route from R1 (would expect to prefer the route from Hub2)

--> Hub2 prefers the external route from R2 (expected behavior)

 

--> If R1 stops advertising 10.10.10.10/32, then Hub1 will receive the route from Hub2 via iBGP with AS PATH 65100 200

 

--> If Spoke 1 has in the hub list HUB1(primary) HUB2(secondary), it will prefer the route from HUB2 with AS PATH 65100 200

 

thanks

 

 

 

 

4 Replies 4
CptnCrnch
Kind of a big deal
Kind of a big deal
CSV
Comes here often

Hi CptnCrnch,

 

My post is not related to your link.

 

thanks

 
PhilipDAth
Kind of a big deal
Kind of a big deal

I haven't seen any documentation covering the BGP path selection process.

MarcoSch
Here to help

Hi,

 

Do have a look at the following CiscoLive 2018 presentation: BRKCRS-2103 Integrating the Meraki SD WAN Solution with the traditional Enterprise network. The presentation covers several subjects including BGP based path selection for a one-armed concentrator.

 

The presentation and recording should be available via ciscolive.com

 

Regards,

Marco.

Get notified when there are additional replies to this discussion.
Welcome to the Meraki Community!
To start contributing, simply sign in with your Cisco account. If you don't yet have a Cisco account, you can sign up.
Labels